<?php
$allowed_image_types = array('image/pjpeg'=>"jpg",'image/jpeg'=>"jpg",'image/jpg'=>"jpg",
'image/png'=>"png",'image/x-png'=>"png",
'image/gif'=>"gif");

$allowed_image_ext = array_unique($allowed_image_types); // do not change this
print_r($allowed_image_ext); echo "<br/>";
$image_ext = "";	// initialise variable, do not change this.
foreach ($allowed_image_ext as $mime_type => $ext) {
    $image_ext.= strtoupper($ext)." ";
    echo $image_ext."<br/>";
}
?>
